SU916745A1 - Composition for isolation of water inflow from formation - Google Patents

Description

The invention relates to oil-producing curse, in particular to the isolation of water inflows from the reservoir to enhance its oil recovery.

. A known composition for the isolation of layers containing cement, alkali metal silicate or ammonium, sodium chloride and water [11.

The use of this composition is not effective enough because of its rapid premature setting. .

A known composition for isolating water inflow from the reservoir, containing sodium sulfate, calcium chloride and water [2].

The disadvantage of its use is the premature formation of a blocking agent - gypsum before the composition enters the reservoir.

The purpose of the invention is to improve the insulating properties of the composition in a carbonate reservoir.

This goal is achieved by the fact that the known composition for isolating the water inflow of the reservoir Che, containing sodium sulphate and water, is additional. It contains hydrochloric acid and ammonium sulphate in the following ratio of components, wt.%;

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Sodium sulfate in terms of anhydrous 5,1-12,5

5 Hydrochloric acid in terms of

hydrogen chloride 4.5-12.3

Ammonium sulphate 0.02-14.5

Water Rest

You can prepare the proposed composition in advance.

These components are soluble and do not react with each other. They also do not cause intense corrosion of the equipment, since inhibited hydrochloric acid can be used to prepare the composition. The results in the dissolution of all components of the true tensile-θ thief containing no solid particles ^m. In such a constant form, it can not only be stored, but also transported to any distance. It does not change its chemical composition in the process of pumping 25 through tubing pipes until it gets into the carbonate zone. Since the proposed composition is a true aqueous solution, its viscosity is significantly less than 30 viscosity of any emulsion. therefore

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This composition easily penetrates through any form of deep cracks into the carbonate formation, where the formation of solid particles, which contribute to the isolation of water inflow, occurs.

The formation of clogging material is very simple. Hydrochloric acid, which is one of the components of the proposed composition, once in the carbonate reservoir, immediately begins to react with the carbonate layer 10

2ns? + CaCO ₃ = CaC " ₂ + H _g 0 + CO _a (1)

The resulting calcium chloride, in turn, interacts with the sulphates located here: 15

CaC <1 + Na _g 8O4 + 2H _g O "Ca8O4 x x 2H _X O + 2 Yase (2>

Sacey _{s + (ΝΗ4.) Χ 8Ο $} + 2Η * 0 = ^ SaZO 2N xx> o + 2mtsre (3)

in ionic form, the equation of reactions (1), 20 (2) and (3) is as follows: _{g +}

2H + CaCO _e = Ca + TH ₂ O + COA (4)

Ca ²⁺ + 80 ^ + 2Н ₂ О = СаЗО4> 2Н _X О (5)

The proposed composition is checked in;> 5 laboratory conditions as follows.

Ie two polished tightly compressed marble plates prepare an artificial crack. The crack is sealed from the sides, after which both marble plates are also sealed in a special metal block with entrances and exits.

First, a 10% solution of sodium chloride is pumped through an artificial crack and the crack permeability is determined. Then through it serves the proposed composition in its various variants. After 5-6 hours after this, a 10% aqueous solution of sodium chloride is again injected into the crack and its permeability is again measured.

The results are shown in the table.

After each experiment, the crack model is disassembled, the marble plates are thoroughly cleaned of sediment and again used for the next experiment. After 2-3 experience they are replaced by new ones.

pp Used composition, weight. % Permeability cracks, MD 30 ^ | her | (ID / FARS | n ₂ ° before experience [after experience one 5.0 2.5 o; o1 92.49 5 30 280 2 8.0 4.2 0.01 87.79 540 122 3 12.0 6,6 0.03 81.37 571 7.1 four 13.0 7.0 0.05 79, 95 498 4.5 five 5.1 5.3 4.5 85.1 510 12.2 6 5.1. 8.2 9.0 77.7 475 6.4 7 5.1 12.3 14.5 68.1 490 0.8 eight 4.8 11.4 15.0 68,8 522 13.2 9 4.8 12.5 15.0 67.7 • 524 18.6

In the table, the amount of salts taken

V. recalculated to the anhydrous state. The amount of hydrochloric acid is shown in terms of hydrogen chloride, 55 and the amount of water takes into account the water contained in the acid and salts.

If, in the proposed composition, the amount of salts for each experiment is chosen arbitrarily, then the amount of malic acid is determined by the consumption of salts plus a slight excess. In other words, the acid consumption is determined by its stoichiometric ratio with the sulfations.

'In the first experiment, a composition containing a small amount of salts was chosen. As a result, the gypsum, although formed in the crack, is not enough to fill the entire volume of the gap. Nevertheless, the formation of sediment leads to the fact that the permeability of the crack is almost halved. An increase in the amount of sodium sulphate in the composition leads, as a result of the reactions (2) and (1), to an even greater blockage of the crack. Further increase in the content of sodium sulfate ho5

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This leads to a sharp decrease in the permeability of the crack, but it is already “difficult” to achieve due to the low solubility of sodium sulfate. In subsequent experiments, it is possible to achieve a very significant reduction in the permeability of the crack (75–600 times smaller than the initial one), which indicates a successful selection of the composition by introducing an increased amount of ammonium sulfate. ten

· In two recent experiments done ^- "an attempt to increase the amount of acid in order to accelerate the process. However, an excessive amount of acid, although it contributes to the apparent acceleration of reaction 15 and the complete binding of sulfate ions, but the additional volume of marble dissolved in this acid leads to an increase in permeability, which, of course, is undesirable. 20 On the basis of the experimental data obtained, the quantitative (minimum and maximum) boundaries of the composition specified above were established. _and 25

The results obtained are additionally verified by treating several oil wells during the field testing of the proposed composition. The results of this test are quite satisfactory, because after each treatment the inflow of formation water from the well decreases, and the flow of oil increases.

The density of carbonate rock is 2.93 gf / cm ⁵ , while the density of gypsum is 2.3 gf / cm ¹ .

If under the action of acid one gram-mole of carbonate dissolves, i.e. If 100 g of it is present, then the amount of calcium ions appears in the solution, which, together with sulphate ions, gives a gram-mole of gypsum, i.e. 172 g of its 100 g of dissolved carbonate (according to the reduced density) - 45

occupies a volume of 34 cmL But the formed gram-mole of gypsum occupies a volume of 74 cm3 even in a compressed state. In reality, however, gypsum crystals occupy an even larger 50

volume in the crack, because they are in a loosened state. Thus, the gypsum formed as a result of the chemical interaction of the proposed composition with the carbonate 55 rock not only fills the volume

Compiled by N.

Editor L. Fil Techred M. Teper

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previously occupied by carbonate but also closes the cracks in which it is formed, Consequently, the proposed composition allows to obtain a reliable blockage of the most drained part of the carbonate reservoir along the crack, where it penetrates, i.e. is more effective than the famous.

Example 1. A well 91 of the Abino-Ukrainian deposits before treatment has an oil flow rate of 0.2 tons / day, water is about 0.2 tons / day. The well was treated with 4600 kg of a solution of the following composition, wt.%: Ν3 ₂ 5Οψ5.1 (235 kg); PSE 4.5 (207 kg); (MP ₄ ) _g OO4 0.02 (0.9 kg); water 90.4 (4157 kg). The well is aged for 24 hours. After treatment, the well daily gives 1.2 tons / day of oil with a reduced water content of up to 1 ton / day.

Example 2. A well 72 of the Abino-Ukrainian field has a production rate of oil before treatment of 1.5 tons / day and water of 1.4 tons / day. The well was treated with 6000 kg of a solution of the following composition, wt.%: ΝΒ ^ δΟιψτδ, Ο (480 kg); HCE 9.2 (952 kg); (NLIbSTs 6.0 (370 kg); water 76.8 (4964 kg).

After treatment, the well has a production rate of 4.3 tons per day, water 3.6 tons per day.

Claims (1)

Claim The composition for isolating water flow from the formation, containing sodium sulfate and water, is different in that, in order to improve its insulating properties under carbonate formation conditions, it additionally contains hydrochloric acid and ammonium sulfate in the following ratio of components, wt.%: Sodium sulfate in terms of anhydrous 5,1-12,5 Hydrochloric acid in terms of hydrogen chloride 4,5-12,3 Ammonium sulphate 0.02-14.5 Water Rest